EP0060352A1

EP0060352A1 - Building structure

Info

Publication number: EP0060352A1
Application number: EP81200605A
Authority: EP
Inventors: Auko Anton Smid; Hubertus Marcellus Petrus Antonius Geenen
Original assignee: Stahlton AG; Ingenieursbureau voor Systemen en Octrooien Spanstaal BV
Current assignee: Stahlton AG; Ingenieursbureau voor Systemen en Octrooien Spanstaal BV
Priority date: 1981-03-13
Filing date: 1981-06-02
Publication date: 1982-09-22
Also published as: DE3165216D1; ATE8804T1; EP0060352B1

Abstract

To save material in a building structure, consisting of columns and floors, the floors are proportioned taking into account that they are clamped in the columns.

Description

The invention relates to a building structure, comprising a plurality of columns and at least one floor supported by said columns, said floor comprising a grating of floor girders connected with the columns and floor slabs supported by the floor girders, which are provided with stretching cables extending inside a punch region above the columns.
Such a building structure is known from "Sonder- druck aus der S.B.Z., Jahrgang 91, Heft 49" of December 6, 1973. The tendency therein is to construct the floor with a minimum of concrete and reinforcement. The calculation of the floor girders is based on the assumption that the girders are deposited on the columns.
The invention has for its object to save even more material. For this purpose the floor girders and their reinforcement are proportioned on the assumption that the floor girders are each clamped in at least one of the columns, taking the rigidity of the column concerned into account.
The design can be based on a chosen column dimension. The floor girders as well as each column in which said floor girders are clamped and their reinforcement are preferably proportioned on the assumption that the floor girders and the columns are interconnected in clamps taking into account the rigidity of the column concerned or the rigidity of the floor girder respectively. Thus a maximum saving of material can be obtained by selecting the rigidity of columns and floor girders so as to match one another.
Preferably, all floor girders and their reinforcement are proportioned on the assumption that the floor girders are also clamped in columns standing at the edge of the floor, taking into account the rigidity of said columns.
The floor slabs may be laid down on the floor girders, but preferably the floor girders and the floor slabs constitute a plate-shaped monolith of substantially uniform thickness.
Preferably, the stretching cables are bent over outwardly, viewed from the upward direction, at least into a horizontal direction near the rims of the floor above the columns in this area.
By said bending, part of the load is directly transferred to the column standing at the edge of the building structure, so that shear stress due to punching effect is reduced.
The invention will be described more fully hereinafter with reference to a drawing.
The drawing schematically shows in:

figure 1 a side elevation of part of a building structure embodying the invention,
figure 2 a plan view of the part shown in figure 1, figure 3 an enlarged, perspective view of detail III of figure 1 in a variant of the building structure shown in figure 1,
figure 4 an enlarged sectional view taken on the line IV-IV of figure 2,
figure 5 an enlarged sectional view taken on the line V-V of figure 2,
figure 6 a variant of the structure of figure 5,
figures 7 and 8 a plan view and a side elevation respectively of a diagram of the stretching cables of a floor of the building structure shown in figure 1,
figures 9 and 10 each a diagram of the floor load corresponding to the prior art dimensions and to the dimensions according to the invention respectively,
figure 11 on an enlarged scale detail XI of figure 1,
and figure 12 on an enlarged scale detail XII of figure 5 during the building operation.

The building structure 1 embodying the invention comprises a plurality of columns 2, 3, that is to say, inner columns 2 and peripheral columns 3, and a plurality of floors 4. Each floor 4 comprises a grating of floor girders 5 connected with the columns 2, 3 and floor slabs 6 supported by the floor girders 5.
Figure 3 shows that the floor girders 5 can form a grating having recesses 11, which are covered by floor slabs 6 (not shown) lying on the floor girders 5, but preferably the floor girders 5 and the floor slabs 6 constitute a plate-shaped monolith of substantially uniform thickness as is illustrated in figures 1 and 2.
The floor girders 5 extend through the punch region 8 indicated in figure 4 by dot-and-dash lines 7 across the columns 2, 3 and have uninterrupted stretching cables 9 and 10 respectively, which extend preferably, but not necessarily from one edge 12 to the opposite other edge 12 of the floor 4. If the floor girders 5 form a monolith with the floor slab 6, they have a width of about 1/6th to 1/3rd of the span between the columns 2, 3, so that some of the stretching cables 9, 10 may extend outside the punch region.
As shown in figure 8, the stretching cables 9, 10 with sufficient concrete coating extend in the middle of the floor girders 5 at the lowest possible level and above the columns 2, 3 at the highest possible level, so that they have a slight S-bend on either side of the middle 13 of the columns 2. Likewise on the inner side of the middle 14 of the peripheral columns 3 the stretching cables 9, 10 have an S-shaped bend, of which figure 6 only shows the upper part. In other words, the stretching cables 9 and 10 are bent over near the edges 12 above the local peripheral columns 3 - viewed in outward direction - from the upward direction 15 at least to a horizontal direction 16 (see figure 11). Thanks to this bend the stretching cables 9, 10 directly transfer part of the load to the columns 2, 3 so that shear stress due to punch effect near line 7 in the concrete 2 is reduced. The stretching cables 9 and 10 are arranged in envelopes 18 and stuck to said envelopes 18, as the case may be, by means of an adhesive introduced through hoses 17 after the stretching cables 9, 10 have been pre-stressed and fixed to anchors 19.
Figure 12 shows the disposition known per se of the anchor with respect to a casing plate 20 prior to pouring of the concrete 21. Apart from the stretching cables 9, 10 the floor 5 comprises mild steel reinforcing networks 23. The columns 2, 3 comprise steel reinforcing bars 24, each extending throughout the column 2, 3 concerned.
The floor girders 5 and their reinforcement, in particular the stretching cables 9, 10 are proportioned on the assumption that the floor girders 5 are each clamped tightly in the columns 2, 3 taking into account the rigidity of the columns 2, 3.
In the load diagram of figure 9 the floor is assumed to be disposited on the girders and hence the maximum bending moment M₁ on the floor girders in the peripheral region 25 will be about 1/12 ql² for a span 1 and a theoretically uniformly distributed load g. On the contrary, in the case of a perfectly rigid clamping as shown in figure 10 in the peripheral region 26 the maximum moment M₂ is equal to 2 about 1/24 q1². In proportioning the floor girders 5 and their reinforcement in accordance with the invention neither about 1/12 q1² nor about 1/24 q1² are taken into account, but an intermediate moment is considered, because presumably the columns 2, 3 will not be perfectly rigid. Their rigidity is accounted for in the calculations. This results in that the floor girders 5 and their reinforcement according to the invention can have smaller dimensions, which implies considerable saving of material. Preferably the floor 4 has a uniform thickness d throughout its surface. Therefore, the aforesaid peripheral region 26 is determinative of the floor thickness d. It is even more preferred to construct the inner columns 2 and particularly the peripheral columns 3 with such a rigidity that the calculation concerned is a near approximation of that of figure 10. It is still more preferred to choose an optimum situation in which the cost of the columns 2, 3 and the floor girders are minimized. This can be achieved by selecting the rigidity of the floor girders 5 and that of the floor columns 2 and 3 and/or the span between the columns 2, 3 so as to match one another. Comparing figures 5 and 6 it will be obvious that the invention can be applied in the case of a rim 12 protruding like a collar or not protruding.

Claims

1. A building structure (1), comprising a plurality of columns (2, 3) and at least one floor (4) supported by said columns (2, 3), said floor (4) comprising a grating of floor girders (5) connected with the columns (2, 3) and floor slabs (6) supported by the floor girders (5), which are provided with stretching cables (9, 10) extending inside a punch region (8) above the columns (2, 3), characterized in that the floor girders (5) and their reinforcement (19) are proportioned on the assumption that the floor girders (5) are each clamped in at least one of the columns (2, 3), taking the rigidity of the column (2, 3) concerned into account.

2. A building structure as claimed in claim 1, characterized in that the floor girders (5) as well as each column (2, 3) in which said floor girders (5) are clamped and their reinforcement (19) are proportioned on the assumption that the floor girders (5) and the columns (2, 3) are clampingly interconnected, taking the rigidity of the column (2, 3) concerned or the rigidity of the floor girder (s) concerned into account.

3. A building structure as claimed in claim 1 or 2, characterized in that all floor girders (5) and their reinforcement (19) are proportioned on the assumption that the floor girders (5) are also clamped in columns (2, 3) standing at the edge (12) of the floor (4), the rigidity of said columns (2, 3) being taken into account.

4. A building structure as claimed in claim 1, 2 or 3, characterized in that the floor girders (5) and the floor slabs (6) constitute a plate-shaped monolith of substantially uniform thickness (d).

5. A building structure as claimed in any one of the preceding claims, characterized in the the stretching cables (9, 10) are bent over near the edges (12) of the floor (4) above the local columns (3) - viewed in outward direction - out of an upward direction (15) at least to a horizontal direction (16).